Casting thin crystalline strip or amorphous strip requires a critical control of the flow of the melt through the casting nozzle to produce the desired quality and thickness of cast strip. The various angles and openings used in nozzle design have an important influence on the flow of molten material onto a rotating substrate.
Casting amorphous strip continuously onto a rotating substrate has many of the general nozzle parameters defined in U.S. Pat. Nos. 4,142,571 and 4,221,257. These patents use a casting process which forces molten material onto the moving surface of chill body through a slotted nozzle at a position on the top of the chill body. Amorphous production also requires extremely rapid quench rates to produce the desired isotropic structures.
Metallic strip has been continuously cast using casting systems such as disclosed in U.S. Pat. Nos. 4,475,583; 4,479,528; 4,484,614 and 4,749,024 which are incorporated herein by reference. These casting systems are characterized by locating the nozzles back from top dead center or top of the rotating substrate and using various nozzle relationships which improve the uniform flow of molten metal onto the rotating substrate. The walls of the vessel supplying the molten metal are generally configured to converge into a uniform narrow slot positioned close to the substrate. The nozzle lips have critical gaps, dimensions and shape which are attempts to improve the uniformity of the cast product.
The prior nozzle designs for casting have not provided a uniform flow of molten metal onto the rotating substrate. The critical nozzle parameters have not been found which control stream spreading upon exiting of the nozzle, rolling of the stream edges, wave formation and the formation of a raised stream center.
The present invention has greatly reduced these nonuniform stream conditions and provided a more consistent flow by a nozzle design which requires the critical control of several nozzle parameters.